XENOBIOTIC METABOLISM



The figure above is a stereo figure of colour contour maps of CYP1A2 CoMFA. In the red areas more negative partial charge increase inhibition potency and in the green areas bulkier groups increase inhibition potency. Blue and yellow represent areas where negative partial charge and bulkier groups decrease inhibition potency, respectively. The reference structure is 2,7-dimethylquinoline.

DESCRIPTION OF RESEARCH  

Xenobiotic metabolism plays a critical role in the elimination of foreign compounds in the body. Usually metabolism results in ending the effects of drugs or toxic compounds, but often the same system causes them to become active and toxic. The xenobiotic metabolism research group at the Department of Pharmacology and Toxicology focuses on the function and regulation of selected cytochrome P450 (CYP) enzymes. In addition to conventional laboratory methods, we use increasingly computational (in silico) methods to carry out research. 

An example is the use of the 3-dimensional structure-activity relationship (3D-QSAR) method to study the active sites of CYP enzymes. In this approach, we first generate a dataset based on the ability of chemicals to inhibit CYP activity in vitro. Then, using a specific 3D-QSAR method, CoMFA (Comparative Molecular Field Analysis), we create in silico models that can predict inhibitory properties of chemicals towards these CYP enzymes. Results in CYP1A2 and CYP2A6 enzymes have been published in 2005. We currently use also protein-based modelling methods, for example homology modelling and crystal structures of CYP enzymes. 

Staff

Senior: Hannu Raunio (Professor of Pharmacology), Risto Juvonen (Professor of Drug Toxicology),
PhD students: Minna Rahnasto, Laura Korhonen, Niina Mähönen, Tuomo Kalliokoski, Kaisa Salminen.
Laboratory staff: Hannele Jaatinen

PROJECTS 

1. Novel in vitro and in silico methods in xenobiotic metabolism studies

- Development of high-throughput screens for testing CYP inhibition in vitro
- In silico modelling of CYP inhibition by xenobiotics
- Further development of in silico methods for analysing CYP active sites
- Development of a “CYP filter”, a method to rapidly screen inhibitory properties of chemical compounds in silico 

Selected publications 1 

Pelkonen O, Turpeinen M, Hakkola J, Honkakoski P, Hukkanen J, Raunio H. Inhibition and induction of human cytochrome P450 enzymes – current status. Archives of Toxicology 82, 667-715, 2008.
Korhonen LE, Turpeinen M, Rahnasto M, Wittekindt C, Poso A, Pelkonen O, Raunio H, Juvonen RO. New potent and selective cytochrome P450 2B6 (CYP2B6) inhibitors based on three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis. British Journal of Pharmacology, 150, 932-942, 2007.
Korhonen L, Rahnasto M, Mähönen NJ, Wittekindt C, Poso A, Juvonen RO, Raunio H. Predictive three-dimensional quantitative structure-activity relationship of cytochrome P450 1A2 inhibitors. Journal of Medicinal Chemistry 48, 3808-3815, 2005.
Pelkonen O, Raunio H. In vitro screening of drug metabolism during drug development: can we trust the predictions? Expert Opinion in Drug Metabolism and Toxicology 1, 49-59, 2005
Pelkonen O, Turpeinen M, Uusitalo J, Rautio A, Raunio H. Prediction of drug metabolism and interactions on the basis of in vitro investigations. Basic & Clinical Pharmacology & Toxicology 96, 167-175, 2005
Taavitsainen P, Honkakoski P, Juvonen R, Pelkonen O. In vitro methods in the prediction of kinetics of drugs: focus on drug metabolism. ATLA 32, 425-430, 2004
Turpeinen M, Nieminen R, Juntunen T, Taavitsainen P, Raunio H, Pelkonen O. Selective inhibition of CYP2B6-catalyzed bupropion hydroxylation in human liver microsomes in vitro. Drug Metabolism and Disposition 32, 626-631, 2004
Asikainen A, Tarhanen J, Poso A, Pasanen M, Alhava E, Juvonen RO. Predictive value of comparative molecular field analysis modelling of naphthalene inhibition of human CYP2A6 and mouse CYP2A5 enzymes. Toxicol In Vitro. 17, 449-455, 2003  

2. Refining CYP2A enzyme structure-activity relationships

- Development of 3D-QSAR and protein-based models of mouse CYP2A5 and human CYP2A6 enzymes
- Systematic search for potent CYP2A6 inhibitors
- Inhibition of nicotine metabolism and elimination using novel CYP2A inhibitors
- Development of the in vivo mouse model for studying nicotine kinetics 

Selected publications 2 

Rahnasto M, Wittekindt C, Juvonen RO, Turpeinen M, Petsalo A, Pelkonen O, Poso A, Stahl G, Höltje H-D, Raunio H. Identification of inhibitors of the nicotine metabolising CYP2A6 enzyme - an in silico approach. Pharmacogenomics Journal 8, 328-338, 2008.
Rahnasto M, Raunio H, Poso A, Wittekindt C, Juvonen RO. Quantitative structure-activity relationship analysis of inhibitors of the nicotine metabolizing CYP2A6 enzyme. Journal of Medicinal Chemistry 48, 440-449, 2005
Rahnasto M, Raunio H, Poso A, Juvonen RO. More potent inhibition of human CYP2A6 than mouse CYP2A5 enzyme activities by derivatives of phenylethylamine and benzaldehyde. Xenobiotica, 33, 529-539, 2003
Poso A, Gynther J and Juvonen R. A comparative molecular field analysis of cytochrome P4502A5/ 2A6 inhibitors. Journal of Computer Aided Molecular Design 15, 195-202, 2001
Juvonen RO, Gynther J, Pasanen M, Alhava E and Poso A. Pronounced differences in inhibition  potency of lactone and non-lactone compounds for mouse and human coumarin 7-hydroxylases (CYP2A5 and CYP2A6). Xenobiotica, 30, 81-92, 2000
Pelkonen O, Rautio A, Raunio H and Pasanen M. CYP2A6: a human coumarin 7-hydroxylase. Toxicology 144, 139-147, 2000  

3. Novel CYP-activated prodrugs

- Development of prodrugs that are activated by CYP enzymes in the body
- Development of potent and specific inhibitors of CYP51 

Selected publications 3 

Huttunen LM, Mähönen N, Raunio H, Rautio J. Cytochrome P450-activated prodrugs: targeted drug delivery. Current Medicinal Chemistry 15, 2346-2365, 2008.
Huttunen KM, Mähönen N, Leppänen J, Vepsäläinen J, Juvonen RO, Raunio H, Kumpulainen H, Järvinen T, Rautio J. Novel cyclic phosphate prodrug approach for cytochrome P450-activated drugs containing an alcohol functionality. Pharmaceutical Research 24, 679-687, 2007.
Kumpulainen H, Mähönen N, Laitinen ML, Jaurakkajärvi M, Raunio H, Juvonen RO, Vepsäläinen J, Järvinen T, Rautio J. Evaluation of hydroxyimine as cytochrome P450-selective prodrug structure. Journal of Medicinal Chemistry 49, 1207-1211, 2006.
Hanna Kumpulainen, Niina Mähönen, Jarkko Rautio, Marja-Leena Laitinen,  Marja Jaurakkajärvi, Hannu Raunio, Risto O. Juvonen, Jouko Vepsäläinen, Tomi Järvinen_. Evaluation of hydroxyimine as cytochrome P450-specific prodrug structure. 

4. Pharmacogenomics

- Pharmacogenetics of CYP enzymes
- Use of chip technology in detection of polymorphic alleles of xenobiotics metabolising enzymes 

Selected publications 4 

Garcia-Martin E, Martinez C, Pizarro RM, Garcia-Gamito FJ, Gullsten H, Raunio H, Agundez JAG. CYP3A4 variant alleles in white individuals with low CYP3A4 enzyme activity. Clinical Pharmacology and Therapeutics 71, 196-204, 2002
Raunio H, Rautio A, Gullstén H and Pelkonen O. Polymorphisms of CYP2A6 and its practical consequences. British Journal of Clinical Pharmacology, 2001.

 5. Regulation of CYP enzymes

- Mechanism of induction of CYP2A5/CYP2A6
- Regulation of CYPs in extrahepatic tissues 

Selected publications 5 

Raunio H, Hakkola J, Pelkonen O. Regulation pf CYP3A genes in the human respiratory tract. Chemico-Biological Interactions 151, 53-62, 2005.
Hukkanen J, Väisänen T, Lassila A, Piipari R, Anttila S, Pelkonen O, Raunio H, Hakkola J. Regulation of CYP3A5 by glucocorticoids and cigarette smoke in human lung-derived cells. Journal of Pharmacology and Experimental Therapeutics 304, 745-752, 2003
Hakkola J, Raunio H, Purkunen R, Saarikoski S, Vahakangas K, Pelkonen O, Edwards RJ, Boobis AR, Pasanen M. Cytochrome P450 3A Expression in the human fetal liver: evidence that CYP3A5 is expressed in only a limited number of fetal livers. Biology of the Neonate 80, 193-201, 2001  
 

COLLABORATION

 Academic:

Prof. Olavi Pelkonen, Dr. Jukka Hakkola (Department of Pharmacology and Toxicology, University of Oulu)
Prof. Antti Poso and Prof. Tomi Järvinen (Department of Medicinal Chemistry, University of Kuopio)
Dr. Paavo Honkakoski (Department of Pharmaceutics, University of Kuopio)
Prof. Garold Yost, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, USA
Prof. Edward Sellers,  Professor, Pharmacology, Medicine and Psychiatry, University of Toronto, Toronto, Canada 

Private companies:

Nicogen Inc (Toronto, Canada)
Novamass Analytical Ltd (Oulu, Finland)
Jurilab Ltd (Kuopio, Finland)
 

Selected reviews in Finnish 

Mensio S, Ojala R, Raunio H. Kliinisesti merkittävät yhteisvaikutukset sairaalassa. Duodecim 123, 1725-1731, 2007.
Raunio H. Merkittävimmät yhteisvaikutuksia aiheuttavat lääkkeet – kymmenen ainetta kärjessä. Suomen lääkärilehti 60, 174-175, 2005.
Laitinen K, Raunio H. Varfariini – uutta tietoa vanhasta lääkkeestä. Suomen lääkärilehti 59, 2712-2714, 2004
Raunio H. Miten lääkkeiden yhteisvaikutusten riski muodostuu? TABU 2/2004, pp. 4-6.
Raunio H, Ojala R. Vähentävätkö mikrobilääkkeet ehkäisytablettien tehoa? Suomen lääkärilehti 58, 1313, 2003
Raunio H, Laitinen K. Mikrobilääkkeiden yhteisvaikutukset – ovatko kaikki makrolidit samanlaisia? Suomen lääkärilehti 58, 1906-1907, 2003
Raunio H. Lääkkeiden yhteisvaikutukset – hallittavissa oleva ongelma. Suomen lääkärilehti 58, 3537-3541, 2003
Raunio H, Ojala R, Laitinen K. Tramadolin yhteisvaikutukset. Suomen lääkärilehti 58, 4826-4827, 2003

updated: 9.2.2009/PM